Measurement Arrangement and Measurement Method for Determining a Constituent Substance or Quality Parameter of Water or Waste Water

ABSTRACT

Measurement arrangement for determining a constituent substance or quality parameter of water by thermal decomposition in a reaction module, delivery of a reaction product to a detector, and evaluation of a detector signal for deriving a value of the constituent substance or quality parameter, wherein the reaction module is an elongated vessel having internal heating, and has a head section into which the sample is introduced, a reaction zone, as well as a foot section, from which the reaction product is output, wherein the reaction module, the heating, and means for the supply of samples and carrier gas are configured such that during the operation of the measurement arrangement an outer head temperature is T H ≤80° C., and an outer foot temperature is T F ≤150° C. at a maximum temperature in the reaction zone of T MAX ≥1150° C.

The invention relates to a measurement arrangement and/or a measurementmethod for determining a constituent substance or quality parameter ofwater or waste water.

For determining the content of certain constituent substances ofwater—and thus the quality of drinking water, process water or else seawater, and of waste water contaminated by organic substances, nitrogencompounds or similar—it is known to evaporate and burn a sample in anatmosphere of inert transport gas (carrier gas) enriched with oxygen andto supply the combustion gas mixture obtained on this occasion to adetector adapted for the detection of carbon dioxides, nitrogendioxides, etc.

As the detectors, (apart from others) infrared detectors have proventheir value for the carbon content, special chemiluminescence detectors,respectively electrochemical sensors have proven their value for thenitrogen content, and so-called coulometric detectors have proven theirvalue for the halide content.

Detection methods based on the combustion of a water sample forcapturing the content of organic constituent substances—the so-calledTOC (total organic carbon)—have gained great dissemination. Here, asmall amount of water together with the transport gas is supplied to afurnace heated to a predetermined temperature by means of resistanceheating, where it is evaporated and burnt almost immediately, and thecombustion gas is supplied to a NDIR CO₂ detector whose display of theCO₂ content constitutes a measure for the C content of the water sample.An advanced realization of this method and a corresponding apparatus aredescribed in DE 43 44 441 C2. An arrangement modified to measure verylow TOC values—such as in ultra-pure water or ultra-pure solutions formedical applications—is described in EP 0 684 471 A2.

In the documents EP 0 887 643 B1 and EP 1 055 927 B1, the Applicantproposed further developed methods of this kind and appropriatelydesigned reactors or general arrangements. An improved loading ofsamples in such a measurement arrangement is the subject matter of theApplicant's document WO 2016/091252 A2.

Document U.S. Pat. No. 5,702,954 describes a multi-stage decompositionmethod for phosphorus-containing vegetable or animal samples of thephosphate content including combustion in the presence of a reducingagent (such as oxygen) and subsequent conversion along with ozone in afurther reaction chamber at ambient temperature. Document US2003/0032194 A1, as well, describes a multi-stage oxidation method whichhad been developed primarily for determining nitrogen and sulfur butalso phosphorus in a sample containing one of these elements. Thermaldecomposition methods using special catalysts or ozone, for example, arealso known from JP 59154358 A or JP 61140863 A.

A measurement arrangement and a measurement method for determining thephosphorus content of waste water samples, which is based on theApplicant's patents/applications mentioned above, are described in theApplicant's document EP 2 115 453 B1.

The invention is based on the task to propose an improved measurementarrangement and an improved measurement method, which can be employedfor various constituent substances of water or quality parameters, allowfor a cost-efficient decomposition of the samples and are easy and safeto handle in practice.

This task is solved in its device aspect by an arrangement having thefeatures of claim 1, and in its method aspect by a method having thefeatures of claim 8. Appropriate further developments of the inventiveidea are the subject matter of the depending claims.

The invention includes the idea of reducing the heat losses on thereaction module of the measurement arrangement by suitableconstructional and control measures, and in particular of limitinghousing temperatures of the reaction module in its head and foot areawhich are critical during operating procedures. The maximum temperaturerequired in the reaction zone for efficient sample decomposition shouldbe guaranteed at the same time. The proposed reaction module and itsoperation method is specifically characterized in that the reactionmodule, the resistance heating or infrared heating, and means for thesupply of samples and carrier gas are configured such that during theoperation of the measurement arrangement an outer head temperature isT_(H)≤80° C., and an outer foot temperature is T_(F)≤150° C. at amaximum temperature in the reaction zone of T_(MAX)≥1150° C.

These measures allow a considerable reduction of the energy consumptionof the reaction module and thus of the measurement arrangement as awhole to be achieved, on the one hand, which represents a considerableadvantage of practical use for the users in case of a mobile operationwith accumulators or batteries. On the other hand, this makes thehandling of the measurement arrangement even safer and easier, and this,as well, represents a considerable advantage for the user.

In a realization of the invention, the reaction module, the resistanceheating or infrared heating, and means for the supply of samples andcarrier gas are configured such that during the operation of themeasurement arrangement a head temperature is T_(H)≤150° C., and a foottemperature is T_(F)≤150° C., in particular 120° C., wherein the maximumtemperature in the reaction zone is T_(MAX)≥1200° C. in particular.

The proposed reaction module and operation method may be used in amodular manner in various measurement arrangements which are designedinter alia for determining nitrogen and/or phosphorus and/or the contentof organic carbon, TOC, or the chemical oxygen demand, CSB.

In advantageous constructional realizations of the invention, it isprovided for the reaction module to have a two-layer or multi-layerthermal insulation comprising a macroporous layer and a microporouslayer. In this case, in particular one of the layers of the thermalinsulation is formed by prefabricated annular resistance heating/ceramicfiber modules, which are known and commercially available under thetrade name Fibrothal®, for example.

In a further appropriate realization, the reaction module is mainlyfilled with a filling of porous ceramic balls. The selection of suitableceramic balls having a size and porosity matched to the case ofapplication, allows the passage or the dwelling time of the sample inthe reaction zone, and possibly specifically also the dwelling time ofthe sample in various temperature ranges of the reaction zone and thusthe T regime of the reaction module as a whole to be optimized. Inpractice-oriented realizations, Al2O3 balls are used, which specificallyhave mean diameters of 6, 4.5, 2.7 and 1.2 mm, wherein at least two,preferably four layers of balls each having different diameters lie ontop of each other, and the thickness of the individual layers may beselected such with respect to the specific application and methodconditions that the oxidation of the constituent substances of waterrelative to the analytes in the measurement gas is reliably guaranteedin the different temperature zones of the reactor.

In practice, realizations have proven to be appropriate, in which thereaction module has an inner wall (or a separate reaction vessel) ofAl2O3 extending at least along the length of the reaction zone, and inthe head and foot areas in each case an CFC insert having an O-ring witha Teflon sheathing as a sealing element.

Aluminum oxide as the reactor material has sufficient temperatureresistance and heat conductivity for the operating conditions, andfurthermore sufficient temperature change resistance for practicaloperation. In case of a potential reduction of the decompositiontemperature, high-performance stainless steel may also be used. Thefurnace head in particular is made of a mechanically reinforcedfluorinated hydrocarbon for thermal insulation. According to theapplication, the furnace foot either is made of a mechanicallyreinforced fluorinated hydrocarbon or of a glass foot having a ceramicbaffle plate for thermally bypassing the hot reaction gas.

In practice-oriented realizations, the head section of the reactionmodule has an injection port for temporarily introducing an injectionneedle or permanently supporting a small supply tube, which injectionport comprises an O-ring which is internally spring-loaded by a siliconpadding or an inserted spring.

In adaptation to this realization, the measurement arrangementspecifically comprises an injection syringe operated by a compressionspring or a step motor for inputting the sample into the reactionmodule. This kind of loading of the reaction module with a sample isknown as such in particular from prior property rights/applications ofthe Applicant. As to details of this loading method, reference maytherefore be made to the prior art such as the document WO 2016/091252A2. Here, a detector is in particular assigned to the compression springor the step motor for detecting the start of an injection process of thesample into the reaction module. This idea of detecting the injectionprocess in conjunction with the use of the detection signal describedfurther below is novel.

An alternative realization of the reaction module has a three-way valveconnected to the small supply tube for optionally introducing the sampleor a rinsing liquid into the reaction module. Here, as well, preferablya detector is assigned to the element causing the sample to be supplied,that is to say the three-way-valve, for detecting the start of theinjection process of the sample into the reaction module. According tothe inventors' studies, this realization has advantages with respect tothe wear resistance of the seal(s) and thus of the maintenanceexpenditure for the measurement arrangement, but may also beadvantageous with respect to the speed of the sample supply and therapid alternating execution of measurement and rinsing processes.

In further realization, setting means are provided at the injection portfor setting the position of the injection needle or the small supplytube in the reaction module. Such settings allow the temperatureprogress in the reaction module and in particular also the temperaturesat its head and foot areas to be influenced to a certain extent.

A realization serves likewise the purpose of a targeted setting of thetemperature progress in which the resistance heating or infrared heatingcomprises a plurality of vertically arrayed, separately driven heatingelements, in particular separate resistance heating/ceramic insulatingmodules. Here, in particular, a temperature sensor and a correspondingcontrol input of a heating control device is assigned to at least one ofthe heating elements, and the heating control device is configured suchthat a heating current can be applied, in particular individually, tothe heating modules as a function of an output signal of the temperaturesensor and in accordance with a predetermined temperature profile of thereaction module.

In a further realization, a heating control device of the resistanceheating or infrared heating has a detector input for receiving aninjection input signal representing a proceeding introduction process ofa sample, and the heating control device is configured such as to varythe heating power of the resistance heating or infrared heating based onthe injection input signal. This measure may in particular beadvantageously combined with the above-mentioned temperature sensorcontrol of the resistance heating or infrared heating, in order to thustake into account the influence of the sample injection process on thetemperature distribution within the reaction module in a differentiatedmanner.

According to the inventors' investigations, a PID control algorithm isadvantageously implemented in the heating control device, whichalgorithm utilizes at least the output signal of a temperature sensorand, optionally, the injection input signal for the temperatureregulation in the reaction module.

On the other hand, the control of the measurement arrangement may beconfigured such that the means for sample supply and carrier gas supplyhave a supply control device for the automatically controlled samplesupply and carrier gas supply which has in particular at least one inputterminal for receiving an input signal delivered from the heatingcontrol device for influencing the automated sample supply and carriergas supply. Here, the sample injection is thus controlled to some extentconsidering the current temperature conditions in the reaction module,and is varied, if need be, with respect to a standard regime.

Method aspects of the invention will largely result from the deviceaspects explained above and will therefore not be described again inmore detail here.

However, reference is made to the aspect that during the input processof a sample into the reaction module, an injection input signal isgenerated for a heating control device of the resistance heating orinfrared heating, and the heating control device is operated such as tovary the heating power of the resistance heating or infrared heatingbased on the injection input signal.

Furthermore, reference is made to the aspect that at least onetemperature sensor is assigned to heating elements of the resistanceheating or infrared heating, and the signals of the or of eachtemperature sensor are supplied to corresponding control inputs of theheating control device, and the heating control device is operated suchas to apply a heating current to the heating elements as a function ofan output signal of the associated temperature sensor and in accordancewith a predetermined temperature profile of the reaction module.

Reference is moreover made to the fact that a PID control algorithm isadvantageously operated in the heating control device such as to utilizeat least the output signal of a temperature sensor and, optionally, theinjection input signal for the temperature regulation in the reactionmodule. Ultimately, it may be provided for the means for sample supplyand carrier gas supply to have a supply control device for automaticallycontrolled sample supply and carrier gas supply and to be operated suchthat temperature fluctuations within the reaction zone are minimized.

Advantages and expedient features of the invention incidentally willresult from the following description of an exemplary embodiment andsubstantial realization aspects of the invention on the basis of theFigures. Shown are in:

FIG. 1 a diagrammatic overall representation of an arrangement accordingto the invention,

FIG. 2 a schematic cross-sectional representation of the substantialportions of a reaction module of a measurement arrangement according toan embodiment of the invention,

FIG. 3 a schematic longitudinal cut representation of an injectionsyringe with an injection needle introduced into the injection portaccording to an exemplary embodiment of the analysis arrangement, and

FIG. 4 a schematic diagram of a further realization of the loading of asample into a measurement arrangement according to the invention.

In the manner of a schematic diagram, FIG. 1 shows the overall structureof an exemplary measurement arrangement 10 for determining variousconstituent substances of waste water or service water. The maincomponent of the arrangement 10 is a reaction module 11 describedfurther below; but another type of combustion furnace (such as with aradiation heating) may as well be employed instead. For the sake ofclarity of the representation, parts which are not essential to theinvention and, for instance, serve the purpose of calibrating andcleaning the measurement arrangement, are omitted in this schematicrepresentation.

A symbolically depicted control unit (controller) 12 controls theoverall process of the sample decomposition and the measurementprocedures and is of course connected to the essential shut-off,transport, heating and determination devices of the arrangement. Theimplementation, connection and operation of such a control device arewithin the skilled person's scope and are based on the methoddescription given further below and the device structure explainedhereinafter.

At the input side, a carrier gas storage 14 having an associated inputvalve device 15 is assigned to the reaction module 11 for providing thecarrier gas for the measurement procedures. Furthermore, the furnace hasa heating control unit 17 for controlling the electrical furnaceheating, and a sample supply device 18 for supplying a sample into asample injection valve 19 of the furnace.

The sample supply device 18 comprises a sample reservoir 20, which maybe disposed at the inlet of a sewage plant, for example, an injectionunit 21 mounted to be displaceable on a transport guide 22, and acorresponding transport control 23. The syringe unit 21 comprises adosing syringe 24 and a step motor 25 for the precisely controllableactuation thereof and thus dosing of a predetermined sample volume.

At the outlet of the reaction module 11, a first cooling stage 26 isarranged comprising a cold trap unit 27, a Peltier cooler 28 and anassociated temperature control 29 having a temperature sensor 29 a on orin the cold trap unit 27. Downstream of the first cooling stage 26, asecond cooling stage 30 is arranged comprising a cooling block 31 havingan associated Peltier cooler 32 and a temperature control unit 33controlling the Peltier cooler 32 and having a temperature sensor 33 a.

A second syringe unit 34 is assigned to the first cooling stage 26,which second syringe unit 34—in analogy to the syringe unit 21 forloading the combustion furnace 1—has an injection syringe 35 with a stepmotor 36 for the precisely controlled actuation thereof. Moreover, thissyringe unit 34 as well is supported on a transport guide 37 to which atransport control unit 38 is assigned for displacing the syringe unitinto a second operational position. This operational position is above aflow-through cuvette 39 into which the needle of the injection syringe35 may engage just as into the cold trap 27. In the Figure, this secondoperational position, just as the initial operational position of thesyringe unit 21, are represented in dashed lines.

At an inlet of the flow-through cuvette 39, a reactant container 41 isconnected via a pump 40, in which reactant container a chemical requiredfor the photometrical determination of phosphorous is stored. Theflow-through cuvette 39 protrudes into a photometer unit 42 configuredfor the photometric analysis of an aqueous sample flowing through theflow-through cuvette 39, and the outlet of which is connected to aphosphorous evaluation stage 43.

At the outlet of the second cooling stage 30, the output line 44 of thecombustion furnace 1 branches out to an NO detector 45, which isconnected to a nitrogen (TN) evaluation stage 46 at the outlet side, andto a CO₂ detector 47, which is connected to a carbon (TOC) evaluationstage 48 at the outlet side.

The operating mode of the measurement arrangement 13 partly arises fromthe above explanations regarding the inventive method but will brieflybe summarized again hereinafter.

By means of the first syringe unit 21, an aqueous sample is taken fromthe reservoir 20, transported to the combustion furnace 1 and injectedtherein. At the temperatures set there, it will be evaporated and burntimmediately, and the resulting combustion gas is conducted out from thefurnace into the output line 44 by means of a carrier gas flow fed fromthe carrier gas reservoir 14. In the condenser the flow of combustiongas/carrier gas is cooled down to a first cooling temperature, at whicha condensate precipitates in the cold trap 27.

By means of the second syringe unit 34, a predetermined amount iswithdrawn from this condensate and brought into the flow-through cuvette39, where it is mixed with the reactant conveyed via the pump 40 foreffecting a photometrical determination process and is supplied to thephotometer unit 42 for phosphorous detection.

In the second cooling stage 30, the flow of combustion gas/carrier gasis cooled down to a second cooling temperature close to 0° C. andsupplied to the gas detectors 45 and 46 for NO and CO₂ determination atthe outlet side of the cooling stage. As a result of the determinationprocesses at the detectors 42, 45 and 47, the corresponding evaluationstages 43, 46 and 48 determine the total phosphorous content (TP), thetotal nitrogen content (TN), and the total content of organic carbon(TOC) of the aqueous sample, which had been taken from the reservoir 20and separated in the combustion furnace 1.

In a schematic cross-sectional representation, FIG. 2 shows essentialsections of a sample combustion furnace (reaction module) 11 in arealization according to the invention, into which a substantiallyelongated cylindrical reaction vessel 13 of stainless steel (drawn inthe Figure outlined in a dashed line) may be inserted. At the lower end(foot end), this reaction vessel 13 has a tubular outlet which can becleaned easily from below for removing salt deposits.

In the shown special two-zone configuration (which is only explainedhere as an example), the furnace 11 has a first, upper heating zone 11a, where a maximum temperature of 800° C. can be reached in thisrealization, and a second, lower heating zone 11 b, where a maximumtemperature of 1250° C. is reached. Both of the heating zones are heatedvia heating modules 11 c, 11 d of a highly temperature resistant specialalloy such as the material Kanthal-Fibrothal®, which modules arearranged in a hollow cylindrical manner around the corresponding portionof the reaction vessel 13.

Due to the different maximum temperatures, the heating modules 11 c, 11d have microporous ceramic fiber insulations 11 e or 11 f of differentthicknesses, and the foot area 119, the area 11 between the heatingzones, and the head area 11 i, 11 j below an aluminum cover 11 k arealso ceramic fiber-insulated. A sample loading and carrier gas supplydevice (not illustrated in the Figure) is provided in the area above thecover 11 k. The entire reaction module 11 moreover is coated with amicroporous outer insulation 11 l which considerably reduces both thetemperature at the outer circumference of the furnace and on the headand foot thereof, and namely during normal operation of the furnace tothe values mentioned further above.

The combustion furnace 11 has a complex temperature sensor system whichis likewise able to contribute to reaching this goal. This temperaturesensor system comprises a temperature sensor 11 m, 11 n in each casearranged in the head and foot area, as well as a temperature sensor 11o, 11 p in each case assigned to one of the heating modules 11 c, 11 d.All of the temperature sensors are connected to corresponding inputs ofa heating control and regulation device which, according to thedesignation of the controller 12 in FIG. 1, is designated 12A. In theheating control and regulation device 12A, the detection signals of thetemperature sensors are processed into driving signals for the heatingmodules 11 c, 11 d according to a stored optimizing algorithm (ifrequired, along with signals S_(INJ), which characterize a sampleinjection process (see further below). The driving signals control thecurrent supply to the modules and thus the heating of the heating zones11 a, 11 b in a time-dependent manner. Advantageously, a PID controlalgorithm is implemented in the heating control and regulation device12A.

The furnace structure shown in FIG. 2 and described above, together withthe selective and controlled heating described, contributesadvantageously to the permanent realization of the high temperatures ofmore than 1200° C. generated specifically in the second, lower heatingzone 11 c, with the special insulation both contributing to a reasonableenergy expenditure and excluding hazards to the environment.

In a schematic manner, FIG. 3 shows an exemplary structure in alongitudinal cut representation and the mutually matched geometricconfiguration of the injection syringe MM and the injection port P ofthe furnace 11 (FIG. 2) of the measurement arrangement (FIG. 1).

The injection port P comprises a guiding sleeve P1 of a substantiallycylindrical configuration in its longitudinal extension, whose diameterand length are matched to the corresponding dimensions of an injectionneedle MM1 of the injection syringe MM, and whose longitudinal axiscoincides with a longitudinal axis LA1 of the furnace which is of acylindrical configuration in its basic shape. At the upper side of theinjection port P, a bore P2 having an enlarged diameter is provided,whose dimensions are matched to those of a needle collar MM2 of theinjection syringe, and whose lower front surface acts as a stop fordepth delimitation when the injection syringe is introduced. An O-ringP3, which may in particular be realized as a silicon ring with a Tefloncoating, rests upon the lower front surface of the bore P2 as a seal. Bymeans of this stop, an exactly predetermined position of the needle end,that is cut off at a right angle to the longitudinal needle axis LA2 ofthe injection syringe, and thus an exactly predetermined injection pointis guaranteed.

In the syringe reservoir MM3, a syringe plunger MM4 is mounted to bedisplaceable longitudinally, whose free end is designed in a usualmanner to draw in a sample manually. At the upper end of the syringereservoir a compression spring MM5 is embedded therein, whose upper endis supported against the upper front wall of the syringe reservoir, andwhose lower end acts upon the end of the syringe plunger MM4. Afterfilling the syringe, the syringe plunger is locked along with thetensioned spring MM5 by means of a locking lever MM6. After releasingthe locking MM6, the syringe plunger MM4 is pressed downward by theforce of the compression spring MM5, and the sample contained in thesyringe reservoir MM3 is injected into the furnace in a predeterminedinterval of time or at a predetermined output velocity.

This output of the predetermined sample amount at an exactlypredetermined velocity or in an exactly predetermined interval of timeis just as important for reproducible analysis results as the preciseinjection position and direction, which are ensured by the specialdesign of the injection needle and the injection port. In a realizationthat is not shown, an adjustable stop or even another kind of device foradjusting the position of the end of the injection needle in the furnacemay be provided, which may also play a role in the context of anoptimized temperature control.

The provision of a position detector D_(INJ) at the locking lever MM6 ofthe injection syringe MM also lies within this context, which positiondetector detects the position of the locking lever and thus the occurredrelease of the compression spring MM5, and thus in turn the initiatedinjection process. The detector D_(INJ) sends an injection signalS_(INJ) to the heating control and regulation device 12A (FIG. 2), whichmay process this signal for providing a drive signal (time and currentintensity) for the heating modules of the furnace. The time-controlledor regulated heating of the furnace thus takes into account theinjection processes which might lead to “temperature surges” in thefurnace for the purpose of smoothing the temporal temperature profileand preventing temperature peaks above the desired maximum values at thefurnace foot.

An alternative embodiment of the sample loading into the reaction module(combustion furnace) schematically illustrated in FIG. 4 works in asimilar way. In this embodiment, a small supply tube T, which ispermanently installed on the injection port P′, is used in conjunctionwith a shut-off or three-way valve in place of a displaceable injectionsyringe. Here, the valve position and thus an occurring injectionprocess may be detected by means of a similar position detector D′_(INJ)as in FIG. 3, or a flow detector is provided on the small supply tube T,which detector likewise detects an injection process and delivers acorresponding injection input signal to the heating control andregulation device of the measurement arrangement.

Incidentally, FIG. 4 shows in a schematic manner that the measurementarrangement may comprise a supply control device for controlling thesample injection, which, according to the designation of the controller12 in FIG. 1, is designated 12B. This supply control device can besupplied with temperature signals of single ones or all of thetemperature sensors 11 m to 11 p (FIG. 2) in order to control injectionprocesses as a function of the temperature signals, that is to say thecurrent temperature status of the combustion furnace 11, by actuatingthe valve V in a differentiated manner.

The realization of the invention is not restricted to the exampleexplained above and the herein emphasized aspects but is likewisepossible in a number of modifications which are within the scope ofskilled action.

1. A measurement arrangement for determining a constituent substanceand/or quality parameter of water or waste water by thermaldecomposition of a sample of the water or waste water in a reactionmodule, delivery of the reaction product to a detector in a carrier gasflow, and evaluation of a detector signal for deriving a value of theconstituent substance or quality parameter, wherein the reaction moduleis an elongated vessel of vertical orientation during operation havingan internal resistance heating or infrared heating, and has a headsection into which the sample is introduced, a reaction zone, where thethermal decomposition is performed, as well as a foot section, fromwhich the reaction product is output in the carrier gas flow, whereinthe reaction module, the resistance heating or infrared heating, andmeans for the supply of samples and carrier gas are configured such thatduring the operation of the measurement arrangement an outer headtemperature is T_(H)≤80° C., and an outer foot temperature is T_(F)≤150°C. at a maximum temperature in the reaction zone of T_(MAX)≥1150° C. 2.The measurement arrangement according to claim 1, configured fordetermining nitrogen and/or phosphorus and/or the content of organiccarbon, TOC, or the chemical oxygen demand, CSB.
 3. The measurementarrangement according to claim 1, wherein the reaction module, theresistance heating or infrared heating, and means for the supply ofsamples and carrier gas are configured such that during the operation ofthe measurement arrangement a head temperature is T_(H)≤70° C., and afoot temperature is T_(F)≤150° C., in particular 120° C., wherein themaximum temperature in the reaction zone is T_(MAX)≥1200° C. inparticular.
 4. The measurement arrangement according to claim 1, whereinthe reaction module has a two-layer or multi-layer thermal insulationcomprising a macroporous layer and a microporous layer.
 5. Themeasurement arrangement according to claim 4, wherein one of the layersof the thermal insulation is formed by prefabricated annular resistanceheating/ceramic fiber modules.
 6. The measurement arrangement accordingto claim 1, wherein the reaction module is mainly filled with avertically layered filling of porous ceramic balls, wherein the meanball diameter in several layers is different.
 7. The measurementarrangement according to claim 1, wherein the reaction module has aninner wall of aluminum oxide or stainless steel extending at least alongthe length of the reaction zone, and/or in the head and foot areas ineach case a reinforced CFC insert having an O-ring with a Teflonsheathing as a sealing element.
 8. A measurement method for determininga constituent substance and/or quality parameter of water or waste waterby thermal decomposition of a sample of the water or waste water with adefined quantity in a reaction module, delivery of the reaction productto a detector in a carrier gas flow, and evaluation of a detector signalfor deriving a value of the constituent substance or quality parameter,wherein the reaction module is an elongated vessel of verticalorientation during operation having an internal resistance heating orinfrared heating, and has a head section into which the sample isintroduced, a reaction zone, where the thermal decomposition isperformed, as well as a foot section, from which the reaction product isoutput in the carrier gas flow, wherein the resistance heating orinfrared heating and/or means for the supply of samples and carrier gasare operated such that during the operation of the measurementarrangement a head temperature is T_(H)≤80° C., and a foot temperatureis T_(F)≤150° C. at a maximum temperature in the reaction zone ofT_(MAX)≥1150° C.
 9. The measurement method according to claim 8,designed for determining nitrogen and/or phosphorus and/or the contentof organic carbon, TOC, or the chemical oxygen demand, CSB.
 10. Themeasurement method according to claim 8, wherein the resistance heatingor infrared heating and/or means for the supply of samples and carriergas are operated such that during the operation of the measurementarrangement a head temperature is T_(H)≤70° C., and a foot temperatureis T_(F)≤150° C., in particular 120° C., wherein the maximum temperaturein the reaction zone is T_(MAX)≥1200° C. in particular.
 11. Themeasurement method according to claim 8, wherein during the inputprocess of a sample into the reaction module, an injection input signalis generated for a heating control device of the resistance heating orinfrared heating, and the heating control device is operated such as tovary the heating power of the resistance heating or infrared heatingbased on the injection input signal.
 12. The measurement methodaccording to claim 8, wherein at least one temperature sensor isassigned to heating elements of the resistance heating or infraredheating, and the signals of the or each temperature sensor are suppliedto corresponding control inputs of the heating control device, and theheating control device is operated such as to apply a heating current tothe heating elements as a function of an output signal of the associatedtemperature sensor and in accordance with a predetermined temperatureprofile of the reaction module.
 13. The measurement method according toclaim 8, wherein a PID control algorithm in the heating control deviceis operated such as to utilize at least the output signal of atemperature sensor, and, optionally, the injection input signal for thetemperature regulation in the reaction module.
 14. The measurementmethod according to claim 8, wherein the means for sample supply andcarrier gas supply have a supply control device for automaticallycontrolled sample supply and carrier gas supply and are operated suchthat temperature fluctuations within the reaction zone are minimized.